text: Shoolery's rule, which is named after James Nelson Shoolery, is a good approximation of the chemical shift δ of methylene groups in proton nuclear magnetic resonance. We can calculate shift of the CH protons in a A–CH–B structure using the formula
  where 0.23 ppm is the chemical shift of methane and the empirical adjustments  are based on the identities of the A and B groups:
  Shoolery's rule is a particular instance of a general class of rules of the form
  with two substituents on methylene resulting in two parameters  and .